Heat exchanger



F. FRGHLICH HEAT EXCHANGER April 6, 1965 3 Sheets-Sheet 1 Filed Jan. 22, 1962 U 1 .m F

PRIOR FRANKLIN S L104 INVENTOR.

Xumm If M ATTORNEY,

F. FROHLICH HEAT EXCHANGER A ril 6, 1965 3 Sheets-Sheet 2 Filed Jan. 22, 1962 FRANKLIN FRb'HL/cH INVENTOR.

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ATTORNEY.

F. FROHLICH HEAT EXCHANGER April 6, 1965 5 Sheets-Sheet 5 Filed Jan. 22, 1962 FRANKLIN FRSALIcI-I INVENTOR.

We 1?. XAMW ATTORNEY.

United States Patent 3,176,763 HEAT EXQHANGER Franklin Friihlich, St. Leonhardstrasse 39, Sankt Gallen, Switzerland Filed Jan. 22, 1962, Ser. No. 167,817

Claims priority, application Switzerland, Feb. 27, 1961,

2,362/ 61 1 Claim. (Cl. 165166) spacing strips arranged between alternate pairs of plates and the plates engaged thereby.

I In my prior Swiss Patent No. 283,884 I have disclosed a heat exchanger unit that consists of a plurality of parallel plates between each pair of which are arranged parallel, spaced spacer strips. The spacer strips are arranged to define between a given pair of plates parallel passages that extend angularly relative to parallel passages defined between the next successive pair of plates. To facilitate mounting of the stack of elements (which are formed preferably of a silicate material, for example, glass) in a heat exchanger housing, it has been found to be desirable to adhesively bond each of the spacer strips to one of the plates engaged thereby. When the elements are pressed together in tight sealing engagement (for example, by gravity loading or by auxiliary clamping means as disclosed in my copending patent application Serial No. 167,816 filed January 22, 1962), first and second heat exchanging fluids may be conducted, respectively, through the passages defined between said successive pairs of plates.

in installations where heat is to be exchanged between large volumes of heat exchanging fluids, a great number of plates having large surface areas are utilized and consequently the size of the unit is quite large. If the unit were of rigid unitary construction, great care would have to be exercised in inserting and mounting the same within the heat exchanger housing without breaking the brittle elernents. Accordingly, it has been found to be desirable to form the unit from a plurality of loosely stacked components that may be readily assembled and clamped together in the housing. As a consequence of this loose stacking, many variations in the mounting of the plates in the housing may be obtained. For example, a method of mounting a plurality of loosely stacked plates in an inclined edgewise manner is disclosed in my copending application Serial No. 150,012 filed November 3, 1961.

The known heat exchanging units have proven to operate quite satisfactorily in installations where the pressures of the two heat exchanging fluids are substantially equal. However, in installations where the pressure of one fluid greatly exceeds that of the other, the disadvantage arises that portions of the plates defining the high pressure passages may be deformed or lifted off of the spacer strips loosely engaged thereby, whereby high pressure fluid leaks into the low pressure fluid stream. Although such leakage of fluid could be avoided by bonding both of the opposed surfaces of each spacer strip to the plates engaged thereby, such a construction would be unitary and would have the installation drawbacks referred to above.

The object of the present invention is to provide improved means for sealing the high pressure passages of a heat exchanger unit of the loosely stacked component type described above. The invention is characterized by the provisionin a heat exchanger unit having spacer strips each provided with a first surface bonded to a heat exchanger plate-of auxiliary means sealing the opposed second surfaces of those outermost spacer strips which lie between alternate pairs of plates. In one embodiment of the invention the auxiliary sealing means comprises a continuous layer of a suitable adhesive such as glue. In a second embodiment the sealing means comprise strips of a resilient compressible material, such as rubber, that are compressedbetween said alternate pairs of plates inter-.

mediate and in contiguous engagement with said outermost spacer strips. Owing to the fact that the heat exchanger unit consists of a plurality of loosely stacked components rather than a unitary assemblage, theunit may readily be assembled and mounted within the heat exchanger housing.

' Other objects and advantages of the invention will bei come apparent from a study of the following specification when considered in conjunction with the accompanying drawing in which:

FIGS. 1 and 2 are perspective and exploded views, respectively, of the heat exchanger unit of the prior art;

FIGS. 3 and 4 are exploded views of two embodiments of the heat exchanger unit of the present invention; and

F168. 5 and 6 are elevational and end views, respectively, of another modification of the heat exchanger unit using resilient sealing strips. l 1

Referring now to the prior art embodiment of FIGS.

l and 2, the heat exchanger unit consists of a stack of spaced, parallel plates 11,12, 13, 14, 15, 16 and 17 betweenwhich are arranged spacerstrips 18, 19, 28, 21, 22. and 23. Both the plates and .thespacer strips are formed from a brittle silicate, such as glass Spacer strips '18, 2d and 22 are arranged to define parallel passages between alternate pairs of plates for conducting a first heat exchanging fluid M in a given direction through the unit. Spacer strips 19, 21 and 23 are arranged to define passages between the remaining pairs of plates through which a second heat exchanging fluid M is directed normal to the direction of fluid M The heat exchanger unit is so mounted in a housing, not shown, that an axial compressive force p is developed to press the'elements of the stack into tight sealing engagement. This compressive force maybe developed by auxiliary clamping means or, when the stack is mounted vertically, by the respective weights of the elements together with additional loading forces applied to the upper plate of the stack. p i

As shown in the prior art embodiment of FIG. 2, stacking of the elements is facilitated by bonding each of the spacer strips to one of the plates engaged thereby. Easily manipulatable exchanger unit components are obtained by gluing spacer strips 118, 19 and 2t) to plates 12, 13 and 14, respectively.

When one of the two fluids M and M has a pressure appreciably greater than the other, the embodiment of FIG. 2 presents the drawback that the pressure forces may lift (or deform by fiexure) portions of one or more of the plates off of the outer spacer strips against which they are pressed, thus causing undesirable leakage of the higher pressure medium into the flow stream of the lower pressure medium. i

A solution of this leakage problem is afforded by the embodiment of FIG. 3 wherein it is assumed that the pressure of fluid M is higher than that of fluid M According to this embodiment, the outermost spacer strips 19' and 21 that define passages for the high pressure fluid are bonded to both of the plates between which they are arranged with the result that the outermost walls of the high pressure passages are completely sealed. Spacer strips 18 and 20' that define the low pressure passages are bonded only to plates 12 and 14, respectively. The innermost spacer strips 19' and 21' need 3,176,763 Patented Apr. 6, 1965 gether in accordance with the size of the unit desired.

Referring now to FIG. 4, it will be assumed that fluid Mi has a greater pressure than that of fluid M In this embodiment, the outermost high pressure passage spacer strips and 22" are bonded to both of the plates between which they are arranged, and the low pressure spacer strips 19" and 21" are bonded only to plates 13" and 15", respectively. The innermost spacer strips Zil" and 22" need only be bonded to plates 14 and 16', respectively. In both FIG. 3 and FIG. 4 embodiments, the means for bonding the spacer strips to the plates consists preferably of uniform continuous layers of an adhesive such as glue. 7

Alternatively, sealing of the high pressure fluid passages may be achieved by the use of compressed, resilient sealing strips as shown in the embodiment of FIGS. 5 and 6. The spacer strips 32 that define the high pressure passages are bonded to plate 31 and the spacer strips 34 that define the low pressure passages are bonded to plate 33. Cylindrical resilient sealing strips are positioned between and contiguous with the outermost spacer strips 32.- Each sealing strip is formed of a resilient compressible material such as rubber, and has-in the normal uncompressed state-a diameter that is greater than the spacing height of spacer strips 32. Consequently, when plates 31 and 33 are pressed toward each other to cause engagement between spacer strips 32 and plate 33, sealing strips 35 are compressed into tight sealing engagement with plates 31 and 33 and the outermost spacer strips 32. Furthermore, upon flow of high pressure fluid through the passages defined by strips 32, sealing strips 35 are deformed outwardly'against the outermost spacer strips 32 to tightly seal the unbonded surface contact joint between the outermost spacer strips and plate 33.

It is apparent that sealing strips having non-circular cross-sectional configurations may be used equally as Well, the only limitation being that the thickness of the sealing strips is greater than the spacing dimension of the spacer strips so that, upon assembly of the 'stack, said sealing strips will be compressed between the plates.

With regard to the embodiments illustrated in FIGS. 3-6 it is important to note that sealing of the innermost spacer strips that define the high pressure passages is not as critical as the sealing of the outermost spacer strips, since leakage of fluid from one high pressure passage to CHARLES 4 another does not adversely affect the operation of the heat exchanger. For the sake of simplicity in the drawings, the thicknesses of the platesand strips have been greatly exaggerated. In actual practice the elements of the heat exchanger unit are rather thin and, owing to the large surface dimensions of the plates, are extremely brittle.

While I have illustrated and described the best forms and embodiments of the invention now'known to me, it will be apparent to those skilled in the art that changes may be made in the apparatus described without deviating from the invention set forth in the following claim.

What is claimed is: A heat exchanger unit, comprising i a first horizontal massive thick brittle plate;

a plurality of coplanar parallel spaced brittle first spacer strips each of which is bonded in fluid-tight sealing engagement with the upper surface of said first plate, the outermost pair of said first spacer strips being adjacent the corresponding edges of said first plate;

a second horizontal massive thick brittle plate bonded in fluid-tight sealing engagement with the upper surfaces of the said outermost pair of said first spacer strips and in contiguous unbonded engagement with theupper surfaces of the remaining first spacer strips, said first and second plates and said first spacer strips defining a plupalityof parallel high pressure passages;

a plurality of coplanar parallel spaced brittle second spacer strips each of which is bonded insealing engagernent with the upper surface of said second plate, said second spacer strips extending in a direction normal to the axes of said first spacer strips, the outermost pair of said second spacer strips being adjacent the corresponding edges of said second plate; and

third horizontal plate means in contiguous unbonded engagement with the upper surfaces of said second spacer strips and cooperating with said second strips and said second plate to define parallel low-pressure passages extending normal to the axes of said high pressure passages, whereby when a plurality of the heat exchanger unit components are stacked upon each other, the weight of the components eifects sealing contact between the contiguous unbonded surfaces thereof.

References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS 1/55 Germany. 6/52 Switzerland.

SUKALO, Primary Examiner. 

